The CamBABS project will study brain structure and behaviour in individuals with one of two disorders of sex development (DSDs) that are characterized by androgen abnormality beginning prenatally: congenital adrenal hyperplasia (CAH), which causes overproduction of adrenal androgens; and complete androgen insensitivity syndrome (CAIS), which involves an inability to respond to androgens, and so an effective lack of androgen exposure. 35 men and 35 women with CAH will be compared to 35 male and 35 female matched controls (healthy volunteers). 35 females with CAIS will be compared to 35 male and 35 female matched controls (again, healthy volunteers). Magnetic resonance imaging (MRI) will be used to map brain structure and aspects of behaviour known to show substantial sex differences, and for which there is evidence of a relationship to prenatal testosterone exposure, will be assessed. The information obtained will provide convergent evidence regarding the influence of testosterone on human brain and behaviour and enhance understanding of the neural mechanisms involved in sexual differentiation of human brain and behaviour, and so will be relevant to the many psychological disorders that differ by sex. It will also be relevant to clinical management of individuals who have experienced testosterone abnormality before birth, for any of several reasons, including genetic disorders, such as CAH or CAIS, or other DSDs, maternal treatment with hormones during pregnancy, or contact with environmental endocrine disruptors.